Download: mbt-a0501.zip
Virus reportClick on the grey area on the right side of the program window. It should work with any button, just be sure to keep the mouse pointer over the grey area when you click.
A defective button switch may sometimes only fail periodically so if you suspect it is defective repeat the above 100 times or more. If defective you may also see different results depending on how you click so try to click normally (fast) as well as with varying time between pressing and releasing the button, e.g. press, wait two seconds, then release. Also try pressing hard as well as gentle.
If you don't see any errors after 100 times the button is usually healthy.